Bottom Line:
Plant-pathogenic fungi and their hosts engage in chemical warfare, attacking each other with toxic products of secondary metabolism and defending themselves via an arsenal of xenobiotic metabolizing enzymes.The third group generates minimal activity with acyl-CoA compounds that bind non-selectively to the proteins.We propose that fungal NAT isoenzymes may have evolved to perform diverse functions, potentially relevant to pathogen fitness, acetyl-CoA/propionyl-CoA intracellular balance and secondary metabolism.

ABSTRACTPlant-pathogenic fungi and their hosts engage in chemical warfare, attacking each other with toxic products of secondary metabolism and defending themselves via an arsenal of xenobiotic metabolizing enzymes. One such enzyme is homologous to arylamine N-acetyltransferase (NAT) and has been identified in Fusarium infecting cereal plants as responsible for detoxification of host defence compound 2-benzoxazolinone. Here we investigate functional diversification of NAT enzymes in crop-compromising species of Fusarium and Aspergillus, identifying three groups of homologues: Isoenzymes of the first group are found in all species and catalyse reactions with acetyl-CoA or propionyl-CoA. The second group is restricted to the plant pathogens and is active with malonyl-CoA in Fusarium species infecting cereals. The third group generates minimal activity with acyl-CoA compounds that bind non-selectively to the proteins. We propose that fungal NAT isoenzymes may have evolved to perform diverse functions, potentially relevant to pathogen fitness, acetyl-CoA/propionyl-CoA intracellular balance and secondary metabolism.

Mentions:
To assess the enzymatic activity of recombinant fungal NAT proteins towards different substrates, assays were performed with the preferred acyl-CoA of each isoenzyme (as identified by the enzymatic and DSF analyses of the previous section) against a representative panel of arylamine and arylhydrazine compounds23. Group I homologues provided higher enzyme activities with acetyl-CoA and lower with n-propionyl-CoA, but the overall specificity pattern with respect to acceptor substrate was similar with both acyl-group donor compounds (Fig. 3 and Supplementary Fig. S5).

Mentions:
To assess the enzymatic activity of recombinant fungal NAT proteins towards different substrates, assays were performed with the preferred acyl-CoA of each isoenzyme (as identified by the enzymatic and DSF analyses of the previous section) against a representative panel of arylamine and arylhydrazine compounds23. Group I homologues provided higher enzyme activities with acetyl-CoA and lower with n-propionyl-CoA, but the overall specificity pattern with respect to acceptor substrate was similar with both acyl-group donor compounds (Fig. 3 and Supplementary Fig. S5).

Bottom Line:
Plant-pathogenic fungi and their hosts engage in chemical warfare, attacking each other with toxic products of secondary metabolism and defending themselves via an arsenal of xenobiotic metabolizing enzymes.The third group generates minimal activity with acyl-CoA compounds that bind non-selectively to the proteins.We propose that fungal NAT isoenzymes may have evolved to perform diverse functions, potentially relevant to pathogen fitness, acetyl-CoA/propionyl-CoA intracellular balance and secondary metabolism.

ABSTRACTPlant-pathogenic fungi and their hosts engage in chemical warfare, attacking each other with toxic products of secondary metabolism and defending themselves via an arsenal of xenobiotic metabolizing enzymes. One such enzyme is homologous to arylamine N-acetyltransferase (NAT) and has been identified in Fusarium infecting cereal plants as responsible for detoxification of host defence compound 2-benzoxazolinone. Here we investigate functional diversification of NAT enzymes in crop-compromising species of Fusarium and Aspergillus, identifying three groups of homologues: Isoenzymes of the first group are found in all species and catalyse reactions with acetyl-CoA or propionyl-CoA. The second group is restricted to the plant pathogens and is active with malonyl-CoA in Fusarium species infecting cereals. The third group generates minimal activity with acyl-CoA compounds that bind non-selectively to the proteins. We propose that fungal NAT isoenzymes may have evolved to perform diverse functions, potentially relevant to pathogen fitness, acetyl-CoA/propionyl-CoA intracellular balance and secondary metabolism.